On Nov. 24, 1971, a man calling himself Dan Cooper hijacked a Northwest Orient flight from Portland, Ore. to Seattle, Wash., collected $200,000 in ransom in Tacoma, and parachuted mid-flight into oblivion, igniting a search that has stumped the FBI for decades.

Author Geoffrey Gray told HuffPost Crime that in the three years he spent researching his forthcoming book "Skyjack: The Hunt for D.B. Cooper", he met numerous people claiming to be siblings, spouses and relatives of the missing man.

Over the years, alleged kin have popped up across the country, among them a widow in Florida and a long-lost brother in Minnesota. Several others have famously taken credit for the crime.

The town of Ariel, Wash. near where Cooper was originally thought to have landed hosts an annual gathering for enthusiasts, many of whom believe they know who the hijacker was. The FBI itself has investigated more than 1,000 "serious suspects," U.S. News reported.

Still, not one has led to an arrest. Whether Marla's uncle L.D. was the real D.B. Cooper may well remain a mystery, but in the annals of would-be Coopers, he's certain to have plenty of company.